After losing his mother during the war, young Mahito moves to his family’s estate in the countryside. There, a series of mysterious events lead him to a secluded and ancient tower, home to a mischievous gray heron. When Mahito’s new stepmother disappears, he follows the gray heron into the tower, and enters a fantastic world shared by the living and the dead. As he embarks on an epic journey with the heron as his guide, Mahito must uncover the secrets of this world, and the truth about himself.